SCSI

SCSI stands for Small Computer Systems Interface and used as protocol to connect servers to back up devices or SAN or other peripheral devices. They are used because they can buffer data and is very fast

iSCSI uses ethernet connectors and cables as its physical transport. Basically using SCSI protocols and commands over ethernet cables and therefore can be used over long distances. A LUN represents an individually addressable (logical) SCSI device that is part of a physical SCSI device (target). In an iSCSI environment, LUNs are essentially numbered disk drives